Substance use magnifies suicide risk by tightening the loop between psychic pain, disinhibition, and access to lethal means. Suicidality with SUD equips teams to detect and defuse risk in real time while advancing recovery. We start with mechanisms: alcohol and benzodiazepines erode inhibition and judgment; stimulants amplify agitation, paranoia, and crash-related despair; opioids intensify hopelessness through withdrawal, pain, and social isolation. Risk is dynamic—peaking during intoxication, acute withdrawal, legal/relationship crises, and post-discharge windows. Assessment must integrate substance timeline (last use, route, setting), withdrawal stage, sleep debt, access to meds or weapons, and prior attempts; screen for trauma, psychosis, pain, and depression. Care is one plan: stabilize intoxication/withdrawal, launch MOUD or anti-craving agents early, and pair them with practical safety moves (means safety, crisis contacts, supervised dosing). We emphasize brief, high-yield psychotherapies—safety planning intervention (SPI), CBT-S, and DBT elements—delivered in EDs, detox, and outpatient settings. Equity matters: stigma, language, rural distance, and financial precarity all widen risk windows; peer support and family partnership can restore contact and hope. Operations close gaps: 24–72-hour follow-ups after ED/hospital, pharmacy synchronization, text-based check-ins, and dashboards flagging missed inductions and no-shows. Measurement is simple and frequent: suicidal ideation intensity, urges to use, sleep regularity, and connectedness minutes. With an integrated approach, Suicidality with SUD, the practical threads from a suicide prevention in addiction conference, and field standards like safety planning intervention convert volatile weeks into survivable, structured recovery.